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15 Cards in this Set
- Front
- Back
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how to tell if a number is divisible by 3
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add its digits, the resulting number should be divisible by 3
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how to tell if a number is divisible by 4
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if number formed by last two digits is divisible by 4, the whole thing is
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how to tell if a number is divisible by 6
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if number is divisible by 3 and 2
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how to tell if a number is divisible by 9
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add its digits, the resulting number should be divisible by 9
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how do you do long division
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I have 2 points (x1, y1 & x2, y2) from a line. how do I get the slope?
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m = (y2 - y1) / (x2 - x1)
order of points doesn't matter at all. |
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how to simplify a square root?
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find n's prime factors. distribute any repeated prime factors away from the rest, and since sqrt(a*a) == a, that's it.
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what's the distribution rule for roots?
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√(a·b) = √a·√b
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how to find the slope of a perpendicular line (given the linear function mx+b)
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-1/m
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what are the hipotenuses for rect triangles with these sides respectively? (1, 1), (1, 2), (1, 3)
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if the proportion between sides are sure to be these, multiply the shortest side's length by the sqrt shown here to get the real hipotenuse length quickly
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como es la regla de 3 simple?
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A → B
C → (C * B / A) |
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how to determine (x', y')?
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x' = x + cos(a) * r
y' = y + sin(a) * r |
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what is actually sin(a)?
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opposite / hypotenuse
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what is actually cos(a)?
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adjacent / hypotenuse
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what is actually tan(a)?
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opposite / adjacent
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